Single-ended low-pressure discharge lamp

Abstract: The invention relates to a single-ended low-pressure discharge lamp comprising a discharge tube filled with gas and additive and sealed in a gas-tight manner and provided with electrodes connected to current conductors at its ends, and an electronic unit provided with a support board and circuit components for operating the discharge tube, and a housing having a base for insertion into a lampholder, and the discharge tube is composed of tube members connected to each other in a way to allow the passage of the discharge. The housing has a hollow base supporting part to accept the electronic unit and a discharge tube supporting part fixed to the base supporting part and holding the discharge tube, and the discharge tube supporting part has a connection portion and a mantle placed around the connection portion, and the mantle is provided with primary adapter members and the base supporting part, with secondary adapter members fitting to the shape of the primary adapter members. The characteristic feature of the invention is that the inside surface 21e of the mantle 21b of the discharge tube supporting part 21 is, in the neighborhood of at least a portion of the primary adapter members 22, provided with support extensions 23 serving for accepting and fixing the support board 14a and made from the material of the discharge tube supporting part 21, while the longitudinal axes 23a of the support extensions 23 are preferably parallel to the axis 21g of the discharge tube supporting part 21.

Description: The invention relates to a single-ended low-pressure discharge lamp comprising a discharge tube filled with gas and additive and sealed in a gas-tight manner and provided with electrodes connected to current conductors at its ends, and an electronic unit provided with a circuit board and circuit components for operating the discharge tube, and a housing having a base for insertion into a lampholder, and the discharge tube is composed of the tube members connected to each other in a way to allow the passage of the discharge, and the housing has a hollow base supporting part to accept the electronic unit and a discharge tube supporting part fixed to the base supporting part and holding the discharge tube, and the discharge tube supporting part has a connection portion and a mantle placed around the connection portion further the mantle is provided with primary adapter portions and the base supporting part with secondary adapter portions fitting to the shape of the primary adapter portions, the primary adapter portions are lugs forming the continuation of the mantle of the discharge tube supporting part and protruding from the edge of the mantle, while the secondary adapter portions are slots sunk into the wall of the base supporting part, further the circuit board is positioned parallel to axis of the discharge lamp. Nowadays, energy-saving light sources are being more and more extensively used worldwide. Their popularity is due to the favorable light output and illumination properties as well as the long life combined with the low energy required. Of the light sources of this kind, perhaps the so-called "compact" fluorescent lamps enjoy the highest popularity. Their essential feature is that they have a discharge tube composed of several tube members placed parallel to each other. Compact fluorescent lamps, although having favorable illumination and economical features, suffer from the disadvantage that - due to the constructional features of these light sources - they are difficult to fit to luminaires designed for conventional incandescent lamps. The problem has become even more severe with the widespread use of electronically operated versions. The reason for this is that in the case of these versions the housing supporting the fluorescent lamp must Incorporate the operating electronic unit as well and the latter requires accessory components for being placed and fixed inside the housing and also needs a substantial amount of space. A solution for placing the circuit board of the electronic unit in the housing in a vertical position is shown in the EP-A-0 534 728, wherein the circuit board has tab members, and an extra circular support member is also used in order to accomplish the horizontal support of the vertical circuit board. Another kind of single-ended discharge tube is shown in US-4,695,767. It is well seen in the Figure of the description that the electronic unit for operating the discharge tube is placed inside the housing. At the same time, the circuit board carrying the electronic components is inserted between the base supporting and the discharge tube supporting parts of the housing in horizontal orientation, i.e. perpendicularly to the axis of the discharge tube. Another solution for placing the electronic unit in the housing is shown in the Hungarian Patent Specification with Disclosure No. T/50531. This has the essential feature that the circuit board is placed longitudinally in the housing and is fixed by bent joining profiles connected to a mounting plate placed perpendicularly to the axis of the discharge tube. The purpose of the invention is to eliminate the disadvantages of known compact fluorescent lamps and to create a single-ended discharge lamp which has a circuit board mounted vertically, i.e. parallel to the axis of the discharge lamp, and the horizontal support of the vertical circuit board is accomplished in a simple way. The conception of the invention is based on the recognition that the above task can be solved if board supports of special shape and position are placed in the discharge tube supporting part which board supports can hold the circuit board. In accordance with the above purpose a single-ended low-pressure discharge lamp according to the invention with the features of the preamble of claim 1 is characterized in that at the neighborhood of the primary adapter portions the discharge tube supporting part has two board supports holding the circuit board and placed on the internal surface of the mantle of the discharge tube supporting part, which board supports are integral portions of the discharge tube supporting part and each board support contains two ribs running side by side and supporting opposite surfaces of the circuit board, which board support protrude from the space of the discharge tube supporting part into that of the base supporting part, further between the two ribs each board support has its longitudinal axis which is parallel to the axis of the discharge tube supporting part. In a preferred embodiment the supporting extensions are formed as two ribs oriented side by side in the direction of the longitudinal axis, placed on the inside surface of the mantle and going on over the inner side of the primary adapter member. Between the two ribs a support shoulder is placed that protrudes from the inside surface of the mantle and/or from the inner side of the primary adapter member. The low-pressure discharge lamp according to the invention has the advantage of enabling the use of discharge tubes consisting of more tube members than the conventional ones and the assembling of these with a housing of unchanged cross-section as well as to place the operating electronic unit in the housing in a simpler way, by making use of a housing of novel design. A further advantage of the invention is that by using a discharge tube supporting part of specific construction both the positioning of the discharge tube supporting part and the base supporting part relative to each other and also the mounting of the electronic unit as well as of the wire connecting this with the current conductors of the discharge tube can be carried out in an automated and safe way, since the board supports protruding from the discharge tube supporting part can provide the right position of the discharge tube supporting part during the automatic mounting process. It should also be considered as an advantage that by making use of the housing according to the invention inserting and fixing the spacer for positioning and insulating the different wires will be simplified. In the followings the invention will be described in more details by means of an example using drawing figures. In the drawings: Fig. 1 is a possible embodiment of the discharge lamp according to the invention, shown partly in section; Fig. 2 is a magnified detail of Fig. 1; Fig. 3 is the section of a detail of Fig. 2, taken along the plane III-III; Fig. 4 is the bottom view of a possible embodiment of the discharge tube supporting part and Fig. 5 is the section of Fig. 4 taken along the plane V-V. In Fig. 1, a possible embodiment of discharge lamp 10 according to the invention is seen. The discharge lamp 10 has a housing 17 composed of a base supporting part 18 and a discharge tube supporting part 21, as well as a screw base 16 fixed to the neck portion 18b of the base supporting part 18 and a discharge tube 11 connected to the discharge tube supporting part 21. In this embodiment the discharge tube 11 is constructed of eight tube portions 11b aligned in essential parallel to each other and of bridging portions 11c connecting the corresponding tube portions 11b in a way to allow the passage of the discharge. The multiple-bent discharge tube 11 produced in this way is stuck into the connection portion 21a of the discharge tube supporting part 21 of the housing 17 using a fixing material 15, e.g. a basing cement. The discharge tube supporting part 21 is obviously provided with eight holes 21d - not seen in Fig. 1 - formed in the connection portion 21a. The two end portions 11a provided with electrodes 12 of the discharge tube 11 and further six end portions 11a connected with bridging portions 11c are fitted into these holes 21d. The electrodes 12 of the end portions 11a of the discharge tube 11 are connected to the support board 14a of electronic unit 14 for operating the discharge lamp 10 via current conductors 13. As is well seen in Fig. 1, the electronic unit 14 is placed in a cavity 20 surrounded by the base supporting part 18 and the discharge tube supporting part 21. The joint between the base supporting part 18 and the discharge tube supporting part 21 - which two parts the housing 17 is composed of - is made by a fixing slot 21h formed in the outside surface 21f of the mantle 21b of the discharge tube supporting part 21 and running around that mantle 21b, and a shoulder 18c protruding from the wall 18a of the base supporting part 18 which shoulder 18c snaps into that slot 21h thus producing a shape-fit joint. To exactly adjust the position of the base supporting part 18 and the discharge tube supporting part 21 relative to each other are enabled by the secondary adapter members 19 placed in the base supporting part 18 and the primary adapter members 22 protruding from the discharge tube supporting part 21. In the present embodiment - as seen also from the detail of Fig. 1 shown in section - the secondary adapter members 19 are provided as slots formed in the wall 18a of the base supporting part 18, while the primary adapter members 22 protruding from the discharge tube supporting part 21 are lug-shaped extensions fitting into these slots. The primary adapter members 22 have supporting extensions 23 for positioning and fixing the support board 14, protruding from the inside surface 21e of the mantle 21b of the discharge tube supporting part 21 and intruding into the cavity 20 of the housing 17 which supporting extensions 23 are formed as ribs 22b continuing on the inner side 22a of the primary adapter member 22. The supporting extensions 23 that are in this case represented by the ribs 22b have longitudinal axes 23a being parallel to the axis 21g of the discharge tube supporting part 21, i.e. of the discharge lamp 10. In Figs. 2 and 3, that portion of the base supporting part 18 and the discharge tube supporting part 21 is shown, which is in the neighborhood of the primary adapter member 22. The magnified detail illustrates how the primary adapter member 22 of the discharge tube supporting part 21 and the secondary adapter member 19 of the base supporting part 18 are connected to each other. The lug-shaped primary adapter member 22 protruding from the edge 21c of the mantle 21b of the discharge tube supporting part 21 exactly fits to the secondary adapter member 19 formed to have the shape of a slot and sunk into the wall 18a, of the base supporting part 18. The primary adapter members 22 and the secondary adapter members 19 only set the proper relative position of the discharge tube supporting part 21 and the secondary adapter member 19. To join the two parts - as mentioned earlier in explaining Fig. 1 - the combination of the support shoulder 18c and the fixing slot 21h is used. It should be noted that both the support shoulder 18c and the fixing slot 21h may have a different shape, moreover, they can be placed differently from that shown here. The only important point is to achieve a shape- or even pressed-fit joint between the two parts. The supporting extension 23 that holds the support board 14a also forms a part of the primary adapter member 22. In this embodiment the supporting extensions 23 are formed as two ribs 22b aligned parallel to each other and to the longitudinal axis 23a of the supporting extension 23. The ribs 22b start at the inside surface 21e of the mantle 21b of the discharge tube supporting part 21 and run over the inner side 22a of the primary adapter member 22 to reach its end. The support board 14a is placed in the space between the parallel aligned ribs 22b. Inserting the support board 14a is performed in a simple way by using the support shoulders 23b. The support shoulders 23b are profiles - in this case hemispheres - protruding from the inner side 22a of the primary adapter member 22 and from the surface of the ribs 22b which faces the support board 14a. It is also obvious that the support shoulder 23b can have various shapes, e.g. a shoulder running along the rib 22b. Figs. 4 and 5 show the discharge tube supporting part 21 of the low-pressure discharge lamp 10 according to the invention. The two main portions of the discharge tube supporting part 21, the connection portion 21a having the holes 21d and the mantle 21b surrounding the connection portion 21a are clearly seen. In this embodiment the number of the holes 21d is identical with the number of the tube members 11b which the discharge tube 11 of the discharge lamp 10 is composed of, as explained in connection with Fig. 1. In the present embodiment the number of the holes 21d is eight. Of these, except for two, three holes have the shape of an "eight curve" formed by eliminating the wall between two adjacent circular holes. It is also seen in Fig. 4 that reinforcing profiles 24 are placed between the holes 21d. These serve for making the walls being thin in themselves resistant to the load represented by the mass of the discharge tube 11. It is also seen that of the three primary adapter members 22 protruding from the edge 21c of the mantle 21b only two ones have the support extensions 23. These two primary adapter members 22 are positioned opposite to each other so that they are able to accept and fix the support board 14a (indicated in Figs. 4 and 5 by a double dash-dot line). In addition, it is seen in Fig. 4 that at the ends of support extensions 23 introducing portions 23c are formed. The introducing portions 23c have a slant surface with a slope towards the sleeve formed between the ribs 22b that produce the support extensions 23 and accepting the support board 14a. They serve to make easier the introduction of the support board 14a between the ribs 22b when automated assembling is used. Based on the Figures shown it can be realized that the multifunction primary adapter members 22 according to the invention substantially reduce the number of parts and components needed to assemble the base supporting part 18 with the discharge tube supporting part 21 and to position and fix the electronic unit 14. This results in a sufficiently large space to accept the discharge tube 11, even if composed of an increased number of tube members 11b without the need for changing the outline dimensions of the housing 17. Based on those described above the design according to the invention can be well utilized to produce compact fluorescent lamps, in particular when versions with a discharge tube composed of six or even more tube members are involved.

Claims: Single-ended low-pressure discharge lamp (10) comprising a discharge tube (11) filled with gas and additive and sealed in a gas-tight manner and provided with electrodes (12) connected to current conductors (13) at its ends, and an electronic unit (14) provided with a circuit board (14a) and circuit components for operating the discharge tube (11), and a housing (17) having a base (16) for insertion into a lampholder, and the discharge tube (11) is composed of the tube members (11b) connected to each other in a way to allow the passage of the discharge, and the housing (17) has a hollow base supporting part (18) to accept the electronic unit (14) and a discharge tube supporting part (21) fixed to the base supporting part (18) and holding the discharge tube (11), and the discharge tube supporting part (21) has a connection portion (21a) and a mantle (21b) placed around the connection portion (21a), further the mantle (21b) is provided with primary adapter portions (22) and the base supporting part (18) with secondary adapter portions (19) fitting to the shape of the primary adapter portions (22), the primary adapter portions (22) are lugs forming the continuation of the mantle (21b) of the discharge tube supporting part (21) and protruding from the edge (21c) of the mantle (21b), while the secondary adapter portions (19) are slots sunk into the wall (18a) of the base supporting part (18), further the circuit board (14a) is positioned parallel to axis (21g) of the discharge lamp (10), characterized in that at the neighborhood of the primary adapter portions (22) the discharge tube supporting part (21) has two board supports (23) holding the circuit board (14a) and placed on the internal surface (21e) of the mantle (21b) of the discharge tube supporting part (21), which board supports (23) are integral portions of the discharge tube supporting part (21) and each board support (23) contains two ribs (22b) running side by side and supporting opposite surfaces of the circuit board (14a), which board support (23) protrude from the space of the discharge tube supporting part (21) into that of the base supporting part (18), further between the two ribs (22b) each board support has its longitudinal axis (23a) which is parallel to the axis (21g) of the discharge tube supporting part (21). Low-pressure discharge lamp (10) according to Claim 1, characterized in that support shoulders (23b) are placed on the ribs (22b).

Inventors: CHAMBERLAIN LEON F, FUELOEP JOZSEF, HARGITAI MIKLOS, LANTOS FERENC, WUERSCHING ISTVAN, CHAMBERLAIN, LEON F., FUELOEP, JOZSEF, HARGITAI, MIKLOS, LANTOS, FERENC, WUERSCHING, ISTVAN, Fülöp, Jozsef, Würsching, István
Applicants: TUNGSRAM RESZVENYTARSASAG
Application year: 1994
Main classification: H01J5
IPC codes: H01J5, H01J61